soil

soil

1. soil porosity 50%

   • soil air
     • can be improved using subsoiler
   • 25% air needed for respiration
   • soil water 25%
     • adsorbtion and capiliary action
       • capiliary water is held in pores in soil aggregates
       • adsorbtion/ hygroscopic: water that is not available to plants ,but held on the surface of soil particles
     • Gravitational water
       • Water moved through soil by gravity
       • Saturation ; When large pores are full of water
         • Field capacity
         • permanent wilting point
         • Available water capacity

2. soil colour

   • Colour determines humus content
   • Dark colour is rich in humus
   • grey colour indicates its low in fertility

3. soil temp

   • the more air in the soil the faster it heats up